Sound producer



March 10, 1942. I. w. cbx 2,276,022

SOUND PRODUCER Filed Nov. 30, 1939 INVENTOR Irvin W C01 ATTORNEYS Patented Mar. 10, 1942 SOUND PRODUCER Irvin W. Cox, Milwaukee, Wis., assignor to Assoelated Electric Laboratories, Inc., Chicago, 111.,

a corporation of Delaware Application November 30, 1939, Serial No. 306,803

2 Claims.

The present invention relates to sound producers and more particularly to horns of the magnetic vibratory type.

A sound producer of the magnetic vibratory type is ordinarily of relatively complicated construction due, primarily, to the fact that it comprises 'a vibratory armature provided with a resilient mounting arrangement and a separate and distinct sound producing diaphragm operatively connected thereto.

Accordingly, it is an object of the present invention to provide a sound producer of the magnetic vibratory type which includes an improved operating circuit arrangement.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of opera tion, together with further objects and operations thereof, will best be understood with reference to the following specification taken in connection with the accompanying drawing in which the single figure is a longitudinal sectional view of a sound producer or horn and a diagrammatic illustration of an operating circuit therefor embodying the present invention.

Referring now more particularly to the drawing, there is illustrated a sound producer or horn embodying the features of the present invention and comprising a magnetic central casing element l0, two end casing elements It and i2 and a megaphone or trumpet IS. The central casing element It comprises a cylindrical body portion I4 and two outwardly extending annular flanges l5 and IS. The and easing element ll comprises a substantially flat end wall I 6 and an outwardly extending annular flange ll; while the end casing element l2 comprises a centrally disposed tubular portion I 8 and an outwardly extending annular flange IS.

The annular flange l5 carried by the center casing element I is provided with an annular iii recess adapted to receive an annular shoulder 2! provided on the annular flange l1 carried by the end casing element H; similarly the annular flange I 6 carried by the central casing element ill is provided with an annular recess 22 adapted to receive an annular shoulder 23 provided on the annular flange I9 carried by the end casing element i2.

Further, the horn comprises a resilient dislishaped diaphragm 24 provided with flat periph eral and center portions 25 and 26 respectively, connected together by an intermediate corrugated portion 21, the peripheral portion 25 of the diaphragm 24 being arranged in the annular recess til provided in the annular flange l5 carried by the central casing element ill and clamped in place by the annular shoulder it provided on the annular flange ll carried by the end casing element ii, the annular flanges l5 and I1 respec tively carried by the central casing element ill and the end casing element ll being retained in assembled relationship by a plurality of bolts 28 carrying nuts on the outer threaded ends thereof. Y Also, the horn comprises a resilient diskshaped diaphragm 29 provided with flat periphanal and center portions 30 and 3| respectively,

connected together by an intermediate corrugated portion 32, the peripheral portion 30 of the diaphragm 29 being arranged in the annular recess 22 provided in the annular flange It carried by the central casing element i0 and clamped in place by the annular shoulder 23 provided on the annular flange it carried by the end casing element it, the annular flanges l6 and 19 respectively carried by the central casing element it and the end casing element 12 being retained in assembled reiationship by a plurality of bolts 33 carrying nuts on the outer threaded ends thereof.

Further, the central casing element l0 comprises an inwardly disposed cylindrical wall it having a cylindrical bore therein, the cylindrical wall 34 being arranged in spaced relationship with respect to the cylindrical body portion it in order to provide an annular cavity 35' therebetween. Also, an annular recess 36 is provided in the cylindrical body portion M of the central casing element In which is adapted to receive an annular flange 31 carried by a magnetic collar 38.. Further, the collar 38 is provided with an inwardly disposed cylindrical wall 3! having a cylindrical bore 40 therein and arranged in spaced relationship with the cylindrical body portion It in order to provide an annular cavity 41 therebetween. The annular flange 31 carried by the collar 38 is retained in place in the annular recess 36 provided in the cylindrical body portion l4 of the central casing element ID by an arrangement comprising an annular ring 42 and a number of screws 43 extending through openings provided in the ring 42 and threaded into tapped holes provided in the cylindrical body portion i4 of the central casing element in. It is noted that the cylindrical bores 35 and 40 respectively provided in' the cylindrical walls 34 and 39 are arranged in alignment with respect to each other along the longitudinal center line of the hdrn, Also, it is noted that the cylindrical walls 34 and 38 extend inwardly toward each other but are arranged in spaced-apart relationship to provide an annular ga 44 therebetween. v

A reciprocating magnetic armature 44 is arranged within the aligned bores 24 and 44 respectively provided in the cylindrical walls 34 and", which is rigidly carried by a shaft 44 supported at the opposite ends thereof by the diaphragms 24 and 24. More particularly, the rear end of the shaft 44 is secured to the central portion 24 of the diaphragm 24 by an arrangement comprising a screw 41 extending through an opening provided in the central portion 24 of the in the central por on 2| of the diaphragm 24 and is retained in place by an arrangement comprising two clamping washers 54 and 4| disposed on v opposite sides of the central portion ii of the diaphragm 29, a spacing collar 42, and a nut 44 threaded on the outer end of the shaft 44. Also.

winding 44, the field winding 42 being disposed in the annular cavity 35' formed between the cylindrical wall 34 and the cylindrical body portion of the central casing element l4, and

the field winding 43 being disposed in the annular cavity 4| formed between the cylindrical wall 39 and the cylindrical body portion i4 oi. the central casing element l4; In other words, the field windings 42 and 48 are arranged in spacedapart relationship; while the operating winding 84 is arranged between the field windings and 44 and extends into the annular gap 44 formed area and proiec through an opening provided it is noted that the outer end of the shaft 44 supports a piston 44 comprising complementary substantially dish-shaped piston elements 44 and 44.

The peripheral portions of the piston elements element 44 being arranged between the spacing C collar 42 of the nut 53. In other words, the ar-' rangement comprising the clamping washers 44 and II, the spacing collar 42 and the nut 44 not only securely fastens the outer end of the shaft 44 to the centralportion 4| of; the diaphragm 24, but this arrangement also securely retains the piston elements 44 and 54 in spaced-apart and assembled relationship upon the outer end of the shaft 44.

Further, the horn comprises an annular substantially T-shaped ring 41 provided with oppositely disposed annular flanges 44 and 44, the annular flange 44 surrounding the tubular portion l4 of the end casing element I2 and being secured thereto by an arrangement comprising a plurality of screws 44 extending through openings provided in the annular flange 44 and threaded into tapped holes provided in tubular portion l4 of the end casing element l2. Finally, the annular flange 44 carried by the ring 51 surrounds the inner end of the megaphone l4 and is welded thereto as indicated at 4|.

The horn is provided with two annular field windings 42 and 43 and an annular operating between the cylindrical walls 34 and 39. In other words, the operating winding 64 is positioned between the cylindrical body portion l4 of the central casing element I4 and the armsture 44.

The arrangement for resiliently mounting the armature 44 comprising the operating shaft 44 and the diaphragms 24 and 24 is so constructed that the resiliency oi the diaphragms 24 and 2! normally bias the armature 44 toward the end casing element Ii into a normal position while permitting movement of the armature 44 out of contact with the cylindrical wall 34 and 44 and the operating winding 44 toward the end casing element l2 against the bias of the resilient diaphragms 24 and 29 into an operated position.

The field windings 42 and 44 are connected in series cumulative relationship in such a manner that when these windings are energized a cumulative fiux is produced in the armature 44, the central casing element i4 and the collar 24, which causes the armature 45 to be moved from its normal position in proximity to the end casing element Ii to its operated position in substantially equal proximities to the respective end casing elements H and 12 against the bias of the resilient diaphragms 24 and 29. The flux produced by the field windings 42 and 44 traverses a magnetic path extending from the cylindrical body portion l4 of the central casing element II by way of the annular flange 21 and the cylindrical wall-44 of the collar 44, the armature 44 and the cylindrical wall 44 to the cylindrical body portion ll of the central casing element l4. When the operating winding 44 is energized, it produces a magnetic fiux which neutralizes the magnetic fiux produced by the field windings 42 and 44, thereby to cause the armature 44 to be returnedto its normal position from its operated position due to the resiliency of the diaphragm 24 and 24. Accordingly, when the iield windings 42 and 43 and the operating winding 44 are energized or 'deenergized, thearmature 44 occupies its normal position. 0n the other hand, when the field windings 42 and 42 are energized and the operating winding 44 is deenergized, the armature 44 occupies its operated position. Hence, the armature 44 may be reciprocated between its normal position and its operated position by causing the field windings 42 and 42 to be steadily energized and the operating winding 44 to be intermittently energized.

The reciprocation of the armature 44 causes the diaphragm 24 to vibrate between the annular flanges l4 and 14 respectively carried bythe central casing element ll and the end casing element l2 and the piston 44 to reciprocate within the tubular portion ll of the end casing element I2. The vibratory movement of the diaphragm 24 and the reciprocatory movement of the piston 44 sets the column of air in the megaphone it into vibration, thereby causing the horn to produce a predetermined note as determined by the aavaoee dimensions of the tubular portion l of the end casing element i2 and th megaphone l3. Further, it is noted that the movement of the piston 54, with respect to the tubular portion l8 of the end casing element It, compensate for the variation of the volume of the tubular portion l8 of the'end casing element l2 and the megaphone l3 incident to the vibratory movement of the diaphragm 29 and the reciprocatory movement of the piston Kit, in order to cause the horn to pro duce a clear note of a substantially constant pitch. The armature 45 of the horn has a natural frequency of reciprocation as determined by the mass of the armature 45, the operating shaft 46, the diaphragms 24 and 29, and the piston 54, the stiffness of the diaphragms 24 and 29 and the reactance of the vibrating column of air in the tubular portion i8 of the end casing element l2 and the megaphone l3. Preferably the natural frequency of reciprocation of the armature is of the order of 200 cycles per second, in order to cause the horn to produce a note having a corresponding pitch.

An electric circuit network is associated with the horn which comprises a source of direct current supply, such as a battery 10, a control switch SH and an automatic switch 13. Preferably the automatic switch 13 is of the magnetic vibratory hermetically sealed type disclosed and claimed in the copending application of Irvin'W. Cox, Serial No. 306,802, filed November 30, 1939. More particularly, the automatic switch 13 comprises a stationary contact 80 and a vibratory contact 8| and is adapted to, be set into operation by an arrangement, not shown, in order to cause the vibratory contact 8| alternately to engage and disengage the stationary contact 80 at a. predetermined frequency. Preferably, the frequency of vibration of the vibratory contact 8| of the.

automatic switch 13 corresponds precisely to the natural frequency of reciprocation of the armature 45 of the horn, as previously explained.

In order to initiate operation of the horn, the automatic switch 13 is first set into operation, thereby to cause the vibratory contact 8| thereof alternately to engage and disengage the stationary contact an thereof; subsequently the con.- trol switch S" is closed. When the control switch 611 is closed a series circuit is completed for energizing the field windings 82 and 63, this circuit extending from the positive terminal of the battery it by way of the conductor C14, the

field winding 63, the conductor C19, the field winding 62, the conductor C11, the conductor C15, the contacts 12 or the control switch S1! and the conductor C15 to the negative terminal of the battery 18. Also, when the control switch SH is closed a circuit is prepared for energizing the operating winding 84 intermittently under the control of the automatic switch 13, this circuit extending from the positive terminal of the battery 10 by way of the conductor C14, the operating winding 64 and the conductor C18 to the stationary contact 80 of the automatic switch 13, and from the negative terminal .of the battery 10 by way of the conductor C15, the contacts 12 of the control switch SH and the conductor C18 to the vibratory contact 8| of the automatic switch 13. Each time the vibratory contact 8| engages and disengages the stationary contact 80 .of the automatic switch 13 the previously traced circuit for energizing the operating winding 84 is completed and interrupted. Accordingly, the field windings 62 and 63 are steadily energized; while the operating winding 84 is intermittently energized, thereby to cause the armature 45 to reciprocate in order to operate the horn as previously explained.

When the control switch S" is returned to its normal position, the previously tracedcircuits for energizing the field windings 62 and 53 and the operating winding 64, are interrupted at the contacts 12 thereof, thereby to cause the operation of the horn 'to be arrested. When operation of the horn is not required, the operation of the automatic switch 13 may be arrested.

While there has been described what is at present considered to be the preferred embodimerit of the invention, it will be understood that various modifications may be made therein, and it is contemplated to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A sound producer comprising a magnetic field structure including a continuous longitudinally extending outer wall and first and second continuous longitudinally extending inner wam, said first and second inner walls being spaced laterally with respect to said outer wall and magnetically connected thereto, said first and second inner walls being spaced longitudinally with respect to each other and having aligned longitudinally extending openings provided therein, a magnetic armature, means for resiliently mounting said armature for reciprocatory movement within the aligned openings provided in said first and second inner walls, said armature having a normal position wherein it is disposed in closer proximity to said first inner wall than to said second inner wall and an operated position wherein it is disposed in substantially equal proximities to said first and second inner walls, said resilient mounting biasing saidarmature toward its normal position, a field winding and an operating winding coupled to said position and that when said field winding and said operating winding are deenergized or energized said armature is moved by its bias from. its operated position to its normal position, and a vibratory diaphragm operatively connected to said armature.

2. A sound producer comprising a magnetic field structure including a continuous longitudinally extending outer wall and first and second continuous longitudinally extending inner walls, said first and second inner walls being spaced laterally with respect to said outer wall and magnetically connected thereto, said first and second inner walls being spaced longitudinally with respect to each other and having aligned longitudinally extending openings provided therein, a magnetic armature, means for resiliently mounting said armature for reciprocatory movement within the aligned openings provided in said first and second inner walls, said armature having a normal position wherein it is disposed in closer proximity to said first inner wall than to said second inner wall and an operated position wherein it is disposed in substantially apart relationship and respectively disposed between said outer wall and said first and second inner walls, an operating winding disposed between said first and second field windings and mutually between said outer wall and said first and second inner walls, said first and second field windings and said operating winding being so connected and arranged that a substantial magnetic flux traverses said field structure when said first and second field windings are energized and said operating winding is deenergized and that no substantial magnetic flux traverses.

said field structure when said first and second IRVIN W. COX. 

